There also exist 128, 256 and 320-bit versions of this algorithm, called RIPEMD-128, RIPEMD-256, and RIPEMD-320, respectively. The 128-bit version was intended only as a drop-in replacement for the original RIPEMD, which was also 128-bit, and which had been found to have questionable security. The 256 and 320-bit versions diminish only the chance of accidental collision, and don't have higher levels of security as compared to, respectively, RIPEMD-128 and RIPEMD-160.

Because the development of RIPEMD-160 was more open than that of SHA-1, one could conclude that it may be less likely that designers left some secret hole in the algorithm. On the other hand, as it is less popular, fewer cryptographers have tried to find holes in it, so it's just as possible that some unplanned, unknown hole exists in the algorithm.